With the development of the wireless communication technology, a user has an increasingly high service requirement for high quality, a high speed and a new service. Wireless communication operators and device providers need to improve a system continuously to meet the requirement of the user. It requires a great amount of spectrum resources to support new services appearing continuously and meet the requirement of high speed communications. The spectrum resource may be quantified by parameters such as time, frequency, bandwidth and allowable maximum emission power.
Presently, limited spectrum resources have been distributed to fixed operators and services, new available spectrum is rare or expensive. In this case, a concept of dynamically utilizing the spectrum is proposed, i.e., dynamically utilizing spectrum resources which have been distributed to some services but are not utilized sufficiently. For example, the Cognitive Radio (CR) technology is proposed, such that an unlicensed user dynamically accesses to a licensed spectrum under constraint of a certain rule, and actual utilization efficiency of the spectrum is improved significantly, thereby alleviating a problem of spectrum resources scarcity to a certain degree.
Multiple transceivers with a cognitive function and related management control units form a Dynamic Spectrum Access (DSA) system. In the dynamic spectrum access system, a secondary user can access to a spectrum of a primary user in the event that the secondary user does not impact the normal communication of the primary user, i.e., the secondary user has to ensure a service quality requirement of the primary user.